Electric watch



April 26, 1966 J. H. REESE ETAL 3,

ELECTRIC WATCH Original Filed Dec. 19, 1958 3 Sheets-Sheet 1 FIG. I.

INVENTORS James H. Reese Peter J. Ser/em/fsos ATTORNEYS April 26, 1966 J, REESE ETAL 3,248,585

ELECTRIC WATCH Original Filed Dec. 19, 1958 3 Sheets-Sheet 2 INVENTORS James H. Reese Peter J. Ser/em/Isos ATTORNEYS April 6, 1966 J. H. REESE ETAL 3,248,585

ELECTRIC WATCH Original Filed Dec. 19, 1958 s Sheets-Sheet s FIG. 5.

INVENTORS James H Reese.

Pefer J. Ser/em/fsos BY 3W +2 ATTORNEYS United States Patent .0

3,248,585 ELECTRIC WATCH .liames H. Reese, Manheirn, and Peter J. Serlemitsos, Lancaster, Pa., assignors to Hamilton Watch Company, Lancaster, Pin, a corporation of Pennsylvania Original application Dec. 19, 1958, Ser. No. 781,807, now Patent No. 3,136,034, dated June 9, 1964. Divided and this application June 19, 1963, Ser. No. 295,858

2 Claims. (Cl. 310194) This application is a division of copending application Serial No. 781,807, filed December 19, 1958, now U.S. Patent No. 3,136,034.

This invention relates to a battery-operated electric watch driven by an impulse motor utilizing a moving coil carried by the balance wheel and more particularly relates to an improved coil assembly and to a method of making the same.

In the manufacture of a balance wheel and coil assembly for a battery-operated electric watch of the type disclosed in assignees copending applications Serial Nos. 409,934, filed February 12, 1954, now Patent No. 2,888,797, 578,843, now Patent No. 2,972,745 and 578,844, filed April 17, 1956, there is provided a small pie or sector shaped coil which is wound of extremely small wire having a diameter on the order of .0006 inch or about /s the diameter of a human hair. the extremely fine nature of the wire, the winding of the coil presents problems which are entirely unknown to the coil winding art as that art relates to larger and more conventional coils.

It has been the practice in the past to wind these coils on a Teflon core and to remove this core after the coil has been suitably impregnated as is described in detail in assignees copending application Serial No. 648,379 filed March 25, 1957, now Patent No. 3,063,136. A metallic connection is then cemented to the inside of the coil, and this is connected to another contact element carried by the balance staff.

While this method is generally satisfactory and operable on a production basis, experience has shown that considerable spoilage results from damage inflicted to the fine wires by the removal of the Teflon core. In addition, cementing of the metallic connector is tedious and expensive.

While it was originally thought that a coreless coil of the foregoing type presented the best answer to the many problems encountered in producing, mounting and utilizing such a coil in timekeeping mechanism, it has now been found that through the use of a particular type of core these same advantages may be retained while also obtaining production advantages which reduce the cost of the finished unit. This discovery is not to be understood as a mere finding that it is more economical to wind a coil about a core which remains in the coil after production, since in practically all instances this practice leads to deleterious effects which are unacceptable in a high quality electric watch. Rather, the present invention relates to a specific core and coil assemblage which has been found to solve most of the difliculties previously encountered with coreless coils without encountering the disadvantages which have normally been found to be associated with cored coils. In addition the invention also presents a unique method for forming such coils.

It is accordingly a primary object of the present invention to provide in a battery-operated electric watch having a balance wheel carrying coil, an improved coil assemblage.

It is another object of the invention to provide in the manufacture of a battery-operated electric watch having Because of a balance wheel carrying coil, an improved process for manufacturing the coil assembly.

It is another object of the invention to provide in a battery-operated electric watch having a coil carried by the balance wheel, an improved coil wound about a metallic core which remains therein.

These and further objects and advantages of the invention will become more apparent upon reference to the following specification and claims and appended drawings wherein:

FIGURE 1 is a plan view of a balance wheel and coil assemblage showing a coil assemblage constructed according to the present invention;

FIGURE 2 is a plan view showing the core utilized in the coil of FIGURE I mounted upon a winding spindle preparatory to winding the coil thereon;

FIGURE 3 is a side elevation showing one step in the process of forming cores of the type shown in FIGURE 2;

FIGURE 4 is a side elevation showing another step in the process of forming these same cores;

FIGURE 5 is a vertical section showing still another step in the process of forming the cores and FIGURE 6 is another vertical section showing still another step in the process of forming the cores.

Referring to FIGURE -1 there is seen a balance Wheel 10 having a cross-bar 12 mounted on a balance staff 14. The cross-bar 12 is skeletonized at 16, so that each radial portion thereof consists of a pair of legs 18. A rim 20 is carried by the cross-bar and supports a series of poising weights 22 in a conventional manner.

' The rim 20 is cut away at 24 and 26 to provide space for mounting a pie or sector shaped coil 28. The coil 28 consists of an arcuate outer side 30, a pair of substantially radial sides 32, and an inner side 34. It will be seen that the junctures of the radial sides 32 and the arcuate side 30 form curvate coil portions 36.

Attached to each curvate coil section 36 is one end 38 of a flat beryllium copper coil supporting bracket 40. The other ends of the coil supporting brackets 40 are attached to the legs 18 of the cross-bar 12 by means of welds 42.

The coil 28 is wound about a core 44 to be described in detail hereinafter. A flexible coil connector 46 has a core engaging portion 48 which makes contact with the core and thereby with the coil itself as is described in assignees copending application Serial No. 781,809 filed December 19, 1958, now U.S. Patent No. 3,015,206. The other end of the coil connector is attached and electrically connected to the contact plate 52 as is also described in further detail in the last mentioned copending application. Inasmuch as the coil connection forms no part of the invention claimed in the present application, it is not described in further detail herein. The brackets 40 are in the form of flat strips which are blanked and pierced in a simple operation and are secured to the coil by cement 54.

Referring now to FIGURE 3, the cores 44 are formed in a production process in the following manner. An elongated mandrel 60 having a peripheral cross sectional shape similar to the inner shape of core 44 and having a slot 62 along one edge thereof, as is shown in detail in FIGURE 5, has wound therearound in helical fashion a strip 64 formed of the metal of which the core is to be constructed, preferably beryllium copper. Suitable end blocks 66 are provided at the ends of the mandrel 60 to permit securing the ends of the strip in order to hold the helical winding in place.

Referring particularly to FIGURE 5, the mandrel 60 is placed between upper and lower clamps 68 and 70 which lock the helical winding in position. Mounted Within the upper clamp 68 is a planar splitting blade 72 which reciprocates in a slot 76 therein. The splitting 3 blade 72 is forced downwardly to cut the contacted portions of the helical strip 64 at '74.

After the helical winding is cut the mandrel 60 pressure between the clamps 68 and 70 is released only enough so that the end blocks 66 may be pressed together to change the helical configuration of adjoining turns to a parallel configuration as is illustrated by comparison of FIGURES 3 and 4, the latter figure showing the result of moving the right end block inwardly. The clamps 68 and 70 are then again fully tightened and a forming blade 78 is substituted for the splitting blade 72. The forming blade is provided with a blunt end 80 and when forced down through the slot 76 forces the cut ends 82 of the core 44 into their final position. Each core then consists of an arcuate portion 84, a pair of radial portions 86 and a pair of reversely and inwardly bent ends 82.

The forming blade 78 is then withdrawn and the cores are stress relieved while still held between the clamps 68 and 70. The cores may then be hardened on the mandrel in a clamped condition or may be removed from the mandrel for the final heat treatment. As will be apparent, the cores may be removed by simply removing one of the end blocks 66 and sliding all of the cores off. The heat treating temperatures necessary to elfect stress relieving and hardening are Well known to those skilled in the art. In the case of beryllium copper stress relieving may be accomplished at 500-650 F. while hardening occurs at 650 F.

Referring to FIGURE 2, the method of holding the cores during coil winding is shown. The core 44 is mounted on a winding spindle 88 which may be provided and utilized in the manner described in detail in assignees copending application Serial No. 648,379, filed March 25,

1957, now Patent No. 3,063,136.

Upon consideration it will be appreciated that the core disclosed provides the following characteristics:

It is non-magnetic in order not to interfere with accurate timekeeping and is incapable of absorbing moisture so that it does not affect the timekeeping characteristics of the watch with changes in humidity. Dimensional accuracy and adequate strength are provided to retain shape and finish during handling in order to permit mass production techniques. In addition to this, the core adds a minimum weight to the coil so as to reduce poising problems and to improve the weight and inertia ratio. Corrosion resistance is excellent.

The method of forming the core is inherently adapted to mass production and produces an excellent dimensional duplication.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing de scription, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

tive, non-magnetic metal.

2. An assembly according to claim 1 wherein said core is made of beryllium copper.

References Cited by the Examiner UNITED STATES PATENTS 3/1884 Ball 31O-268 X 12/1959 Held 310-39 ORIS L. RADER, Primary Examiner.

MILTON O. HIRSHFIELD, Eaaminer. 

1. AN ASSEMBLY FOR A BATTERY OPERATED ELECTRIC WATCH COMPRISING A BALANCE WHEEL, A SUBSTANTIALLY SECTOR-SHAPED COIL MOUNTED ON SAID BALANCE WHEEL, AND A HOLLOW CORE ABOUT WHICH SAID COIL IS WOUND, SAID CORE BEING SUBSTANTIALLY SECTOR-SHAPED WITH AT LEAST ONE INWARDLY TURNED END EXTENDING INTO THE HOLLOW CENTER OF SAID CORE, SAID CORE COMPRISING A STRIP OF NON-CORROSIVE, ELECTRICALLY CONDUCTIVE, NON-MAGNETIC METAL. 